EFFECT OF GIBBERELLIC ACID SPRAYING AND SOAKING OF ...

ACTA AGROBOTANICA
Vol. 63 (2): 155–160
2010
EFFECT OF GIBBERELLIC ACID SPRAYING AND SOAKING OF RHIZOMES
ON THE GROWTH AND FLOWERING OF CALLA LILY
(Zantedeschia SPRENG.)
Abstract
Rhizomes of Zantedeschia, 15-18 cm in circumference
with leaf buds 0.5-1 cm in length, were planted into 20-cm pots
on 15 May 2006 into a medium consisting of peat with a pH
of 6.2, enriched with a slow-release fertiliser Osmocote Plus
(3-4M) and mixed with fresh shredded pine bark at a rate of 3:1
(v:v). Before planting, the rhizomes were soaked for 20 minutes
in a water solution of gibberellic acid at a concentration of 150
mg dm-3 , or sprayed with the same concentration once, twice
or three times, each time after thorough drying. For each round
of spraying, 100 ml of the solution were used. Gibrescol 10 MG
was applied. Gibberellic acid had a similar effect, whether applied
in the form of a solution for soaking or spraying of rhizomes.
The number of sprayings of rhizomes had no effect on the
effectiveness of gibberellic acid. In the cultivar ‘Black Magic’,
rhizome spraying caused earlier flowering, while in ‘Cameo’
a similar effect was obtained by soaking the rhizomes in gibberellic
acid. Gibberellic acid had no effect on the quality of flowers
and the number of leaves. Gibberellic acid had a good effect
on the index of leaf greenness in the cultivars under study.
Key words: Zantedeschia, gibberellic acid, spraying and soaking
of rhizomes, yield, quality, flowers, leaves
INTRODUCTION
The research on growth regulators carried
out in the world is intended to improve the quality
of plants, boost flower crops and reduce production
costs. An ever-wider use is made of gibberellic acid,
and its usefulness in the cultivation of many species
of ornamental plants has been studied for more than
a decade. In the case of geophytes, its effectiveness has
been proved in, e.g., hyacinths, grape-hyacinths, cyclamens
and tulips (S aniewski and Puchalski,
1977; Saniewski et al. 1978; Krause and B o -
rejsza-Wysocki, 1981; Nowak and Rudni-
Beata Janowska 1 , Roman Andrzejak 2
1 Department of Ornamental Plants
2 Chair of Phytopathology, University of Life Sciences in Poznań, Dąbrowskiego 159, 60-594 Poznań
e-mail: beataj@up.poznan.pl
Received: 15.05.2010
cki, 1993; Treder et al. 1999, N owak, 2000). It
also brings good results in growing many species of
the Araceae family by stimulating the development of
flowers (F unnell and Tjia, 1988; H enny, 1989;
Corr and W idmer; 1991, D ennis et al. 1994;
Janowska and Krause, 2001; Janowska and
Schroeter, 2002). Gibberellic acid is also efficient
in the cultivation of calla lilies with colourful spathes
(Harbaugh and Wilfret, 1979, Henny, 1981
and 1983, Henny and Norman, 1999). However,
the soaking of rhizomes generally applied in this species
is not recommendable in phytosanitary terms,
hence other methods of gibberellic acid application
should be sought that would be equally efficient as
the soaking of rhizomes, while protecting the plants
against the spread of bacterial diseases.
The aim of this study was to assess the effect of
rhizome spraying with gibberellic acid on the growth
and flowering of Zantedeschia cultivars with colourful
spathes.
MATERIAL AND METHODS
The cultivars used in the study were ‘Cameo’,
derived from Zantedeschia albomaculata /Hook./
Baill., and ‘Black Magic’ coming from an inter-species
hybrid of Zantedeschia elliottiana /W. Wats./ Engl.
x Z. macrocarpa Engl.
Rhizomes 15-18 cm in circumference with leaf
buds 0.5-1 cm in length were planted into 20-cm pots on
15 May 2006 into a medium consisting of peat with a pH
of 6.2, enriched with a slow-release fertiliser Osmocote
Plus (3-4M) and mixed with fresh shredded pine bark at
a rate of 3:1 (v:v). Before planting, the rhizomes were
soaked for 20 minutes in a water solution of gibberellic
acid at a concentration of 150 mg dm -3 , or sprayed

156
with the same concentration once, twice or three times,
each time after thorough drying. For each round of
spraying, 100 ml of the solution were used. Gibrescol
10 MG was applied, a preparation in the form of microgranules
readily dissolving in water that contains
10% of gibberellic acid. Control – dry rhizomes.
The experiment consisted of 10 treatments (cultivar
x mode of rhizome treatment). Each treatment involved
5 plants in 3 replications.
The plants, grown in a plastic tunnel, were fed
starting with the fifth week of cultivation. Every 10-14
days, solutions of mixed fertilisers, Peters Professional
and brown Superba, were applied at a concentration
of 0.2%. At the start of vegetation, when the leaves
were fully developed, lime saltpetre at a concentration
of 0.2% was foliar applied once.
The earliness of flowering was determined using
the weighted mean of days from the planting of rhizomes
to the flowering of plants, as well as the volume
of crop, peduncle and spathe length, and flower weight.
The number of leaves growing from a single rhizome
The yield of cut flowers of the cultivars under
study significantly depended on both the variant of GA 3
application and the cultivar (Table 2). Irrespective of
the variant, ‘Black Magic’ flowered more abundantly,
with a mean of 3.4 flowers per rhizome. The yield was
observed to have increased after the application of gibberellic
acid in the form of both the rhizome-soaking
and rhizome-spraying solution. No differences were
recorded between the modes of GA 3 application.
When comparing the length of peduncles, this
feature was found to depend significantly on the cultivar
only (Table 2). Significantly longer peduncles, irrespective
of the variant of GA 3 application, were developed
by the cultivar ‘Black Magic’, while in ‘Cameo’ peduncle
length depended significantly on the variant of GA 3
application. The effect produced in this cultivar by the
Beata Janowska, Roman Andrzejak
Table 1
Earliness of Zantedeschia flowering depending on the variant of gibberellic acid application and on the cultivar
Cultivar
dry rhizomes
rhizomes soaked
in GA 3
was calculated, as well as the index of leaf greenness
correlated with chlorophyll content, for which a chlorophyll
meter SPAD-502 was used (G regorczyk
and Raczyń ska, 1997; G regorczyk et al.
1998).
The results were processed statistically by means
of analysis of variance using Duncan’s test for the
grouping of means at the = 0.05 significance level.
RESULTS
When comparing the earliness of flowering of the
cultivars, ‘Black Magic’ was found to bloom a bit earlier
only in the combination where gibberellic acid had
been applied to their rhizomes in the form of a one-time
spraying solution, and in ‘Cameo’, when the rhizomes
were soaked or sprayed three times with it. A slight delay
in flowering was only recorded in the cultivar ‘Cameo’
in the combination where the rhizomes were sprayed
with gibberellic acid twice (Table 1).
Variant of GA 3 application
(150 mg dm -3 )
rhizomes sprayed with GA 3
once twice 3 times
Black Magic 50 50 46 50 49
Cameo 48 43 49 53 43
soaking or spraying of rhizomes with GA 3 was flowers
with peduncles shorter than in the control. The differences
were substantial and ranged from 7.5 to 10.5 cm.
The length of the spathe significantly depended
on the cultivar only (Table 2). Irrespective of the variant
of GA 3 application, ‘Cameo’ developed spathes
shorter by an average of 2.2 cm.
When comparing flower weight, it was found
that this parameter significantly depended on the cultivar
only (Table 2). Flowers with a significantly smaller
weight developed in the cultivar ‘Cameo’.
The number of leaves growing from a single
rhizome depended significantly on the cultivar only
(Table 3). Irrespective of the GA 3 variant employed,
‘Black Magic’ developed more abundant leaves, three
times as many on average as ‘Cameo’.

Effect of gibberellic acid spraying and soaking of rhizomes on the growth and flowering of calla lily (Zantedeschia Spreng.) 157
Table 2
Size and quality of Zantedeschia yield depending on the variant of gibberellic acid application and on the cultivar
Cultivar
dry rhizomes
rhizomes
soaked in GA 3
Variant of GA 3 application (150 mg dm -3 )
rhizomes sprayed with GA 3
once twice 3 times
Yield of cut flowers
Black Magic 2.4 b* 3.7cb 3.6 c 3.8 c 3.7 c 3.4 b
Cameo 1.2 a 2.7 b 3.0 b 2.7 b 2.8 b 2.7 a
Mean 1.8 a 3.2 b 3.3 b 3.2 b 3.2 b
Length of peduncle (cm)
Black Magic 47.8 c 51.0 c 53.9 c 50.0 c 51.6 c 50.8 b
Cameo 35.4 b 24.9 a 27.9 a 27.3 a 27.8 a 28.7 a
Mean 41.6 a 37.9 a 40.9 a 38.6 a 39.7 a
Length of spathe (cm)
Black Magic 11.9 b 12.2 b 12.4 b 12.3 b 12.5 b 12.3 b
Cameo 10.2 a 9.7 a 10.3 a 10.1 a 10.2 a 10.1 a
Mean
Flower weight (g)
11.1 a 11.0 a 11.4 a 11.1 a 11.3 a
Black Magic 21.1 ab 27.8 cd 31.4 d 27.4 cd 28.6 cd 27.3 b
Cameo 24.1 bc 15.1 a 20.6 ab 16.9 a 16.8 a 18.7 a
Mean 22.6 a 21.5 a 26.0 a 22.2 a 22.7 a
*Means followed by the same letter do not differ significantly at the = 0.05 level
Table 3
Number of Zantedeschia leaves and the index of their greenness (SPAD) depending on the variant of gibberellic acid application
and on the cultivar
Variant of GA 3 application (150 mg dm -3 )
Cultivar
dry rhizomes
rhizomes soaked
in GA3 once
rhizomes sprayed with GA3 twice 3 times
Mean
Black Magic 20.4 c* 19.4 bc
Number of leaves
20.1 bc 16.1 b 17.6 bc 18.7 b
Cameo 7.2 a 8.4 a 8.2 a 8.5 a 7.0 a 7.8 a
Mean 13.8 a 13.9 a 14.1 a 12.3 a 12.3 a
Index of leaf greenness
Black Magic 60.1 b 65.7 c 64.1 c 63.0 c 65.8 c 63.7 b
Cameo 50.5 a 53.7 b 53.3 b 55.8 b 58.8 b 54.4 a
Mean 55.3 a 59.7 b 58.7 b 59.4 b 62.3 b
*Means followed by the same letter do not differ significantly at the = 0.05 level
Mean

158
The index of leaf greenness depended significantly
on both the cultivar and the variant of GA 3 application
(Table 3). Irrespective of the cultivar, the lowest
index was recorded in the leaves of the control plants.
The use of gibberellic acid for spraying and soaking
of rhizomes resulted in a significantly more intensive
leaf colour. Irrespective of the variant of GA 3 application,
a significantly higher index of leaf greenness was
observed in ‘Black Magic’.
DISCUSSION
The discovery of natural growth regulators has
opened up new possibilities of regulation of plant yield,
growth, and development. In the case of Zantedeschia
with colourful spathes, the application of gibberellin
acid has greatly improved their flowering, thereby
making them much more attractive to producers, who
can thus offset the substantial costs of the purchase of
rhizomes.
The research to improve the yield of Zantedeschia
with colourful spathes has been carried out for
about 20 years. Studies initiated by foreign researchers
have failed to establish an optimum concentration
of gibberellic acid used in the form of a solution for
soaking rhizomes. Recommendations speak of the application
of GA at concentrations of 50 to 500 mg
3
dm-3 (Funnell and Tjia, 1988; Dennis et al.,
1994; Corr and Widmer, 1999). The research carried
out in Poland has made it possible to narrow down
the optimum concentrations of gibberellic acid to 100-
150 mg dm-3 (Janowska and K rause, 2001;
Janowska and Schroeter, 2002, Janowska
and Zakrzewski, 2006), hence in the present work
gibberellic acid applied for spraying and soaking of
rhizomes had a concentration of 150 mg dm-3 .
Soaking rhizomes before planting is a simple
practice to perform, but unfortunately the rhizomesoaking
solution is a carrier of bacteria, especially very
dangerous Erwinia carotovora ssbp. carotovora responsible
for a disease fatal to Zantedeschia – soft rot of
rhizomes. Hence it is necessary to seek other methods
allowing a safe use of gibberellic acid. J anowska
and Zakrzewski (2006) compared the efficiency
of foliar sprays with gibberellic acid at a concentration
of 150 mg dm-3 with that of rhizome soaking in three
Zantedeschia cultivars. In both methods, their flowering
was more abundant, but soaking the rhizomes in
gibberellic acid proved much more effective. In the
present experiment, apart from soaking the rhizomes in
a water solution of gibberellic acid, this growth regulator
was also used for spraying. It was demonstrated that
irrespective of the variant of GA application, the yield
3
of cultivars ‘Black Magic’ and ‘Cameo’ had increased,
and what is highly significant, the effectiveness of the
Beata Janowska, Roman Andrzejak
acid in all the variants was similar. This good result
suggests that rather than being soaked in gibberellic
acid, rhizomes can be sprayed with it, which is a far
safer practice eliminating the possibility of bacterial
transfer, and less time-consuming too.
When comparing the earliness of flowering of
the cultivars, it was found that in ‘Black Magic’ it was
the spraying of the rhizomes with gibberellic acid that
caused its earlier flowering, while in ‘Cameo’ a similar
effect was obtained by soaking the rhizomes. This is in
contradiction to the results reported by J anowska
and Schroeter (2002), when the use of gibberellic
acid caused a delay in the flowering of Zantedeschia
by 3-4 weeks. A similar pattern was followed
by the cultivars ‘Pink Persuasion’ and ‘Sensation’,
which bloomed several days later (J anowska and
Krause, 2001). A later entry into the period of flowering
after the application of gibberellic acid was also
reported by T reder (2003b) in the cultivars ‘Black
Magic’ and ‘Mango’. In turn, F unnell and Tjia
(1988) obtained an earlier flowering of Zantedeschia
treated with gibberellic acid.
The present research showed that the qualitative
features of flowers, as expressed by the length of
the peduncle and spathe as well as flower weight, significantly
depended on the cultivar only. Much longer
peduncles and more sizeable spathes were developed
by the cultivar ‘Black Magic’. Hence, its flower weight
also was greater than in ‘Cameo’. As follows from
literature reports, the response of plants to gibberellic
acid can vary depending on the cultivar and mode
of application. J anowska and Zakrzewski
(2006) demonstrated that in the cultivars ‘Black Eyed
Beauty’ and ‘Cameo’ the flowers which had grown
from rhizomes soaked in gibberellic acid had the longest
peduncles, and in ‘Treasure’, the shortest. In turn,
foliar-sprayed gibberellic acid caused the formation
of longer spathes only in ‘Cameo’. In ‘Treasure’ gibberellic
acid used for both rhizome soaking and foliar
spraying produced the development of flowers with
shorter spathes. When comparing flower weight, the
authors found that after the application of gibberellic
acid the cultivar ‘Cameo’ had flowers with the greatest
weight, and ‘Treasure’ with the smallest. Treder
(2003a) claims that an increase in the yield of Zantedeschia
goes with flowers having shorter peduncles. This
was corroborated by J anowska and S chroeter
(2002), who reported that in the cultivar ‘Black Magic’
an increase in the crop of flowers as a result of GA 3 application
was accompanied by a shortening of peduncles.
This regularity was not confirmed by J anowska
and Krause (2001) in the cultivars ‘Sensation’
and ‘Pink Persuasion’. T reder (2003b) failed to find
any effect of gibberellic acid on flower weight, but he
did confirm the development of shorter peduncles in

Effect of gibberellic acid spraying and soaking of rhizomes on the growth and flowering of calla lily (Zantedeschia Spreng.) 159
the cultivar ‘Mango’. As D ennis et al. (1994) claim,
however, after the application of gibberellic acid at
a concentration of 25 mg dm -3 the quality of Zantedeschia
flowers was better.
When comparing the number of leaves and the
index of their greenness, it was found that the number
of leaves growing from rhizomes depended solely on
the cultivar. The cultivar with more abundant leaves
was ‘Black Magic’. However, the application of gibberellic
acid boosted the index of leaf greenness. It
appears from the research by J anowska and Z a -
krzewski (2006) that only in ‘Cameo’ fewer leaves
grew from rhizomes soaked in gibberellic acid in the
second year of study. In turn, when applied for rhizome
soaking, this regulator improved the intensity
of leaf greenness in ‘Cameo’ in the first year of study
and in ‘Treasure’ in both years. On the basis of the
intensity of colour in freesia leaves, M ynett et al.
(2001) found that plants grown from bulbs soaked in
gibberellic acid had a significantly higher index of leaf
greenness, which shows its role to be stimulating. As
Corr and Widmer (1991) report, in Zantedeschia
rehmannii the number of leaves developing from rhizomes
largely depends on their size rather than on
treatment with gibberellic acid. Similarly J erzy and
Janowska (2003) state that gibberellic acid does
not affect the number of leaves in Zantedeschia with
colourful spathes.
CONCLUSIONS
1. Gibberellic acid had a similar effect, whether applied
in the form of a solution for soaking or spraying
of rhizomes.
2. The number of sprayings of rhizomes had no effect
on the effectiveness of gibberellic acid.
3. In the cultivar ‘Black Magic’, rhizome spraying
caused earlier flowering, while in ‘Cameo’ a similar
effect was obtained by soaking the rhizomes in
gibberellic acid.
4. Gibberellic acid had no effect on the quality of
flowers and the number of leaves.
5. Gibberellic acid had a good effect on the index of
leaf greenness in the cultivars under study.
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Beata Janowska, Roman Andrzejak
Wpływ opryskiwania kłączy i ich moczenia
w kwasie giberelinowym na wzrost i kwitnienie
cantedeskii (Zantedeschia Spreng.)
Streszczenie
Kłącza o obwodzie 15-18 cm z zawiązkami liści
o długości 0,5-1 cm posadzono 15 maja 2006 roku
do doniczek o średnicy 20 cm, w podłoże składające się
z substratu torfowego o pH 6,2, wzbogaconego nawozem
o spowolnionym działaniu Osmocote Plus (3-4M)
i zmieszanego ze świeżą, rozdrobnioną korą sosnową
w stosunku objętościowym 3:1 (v:v). Przed sadzeniem
kłącza moczono przez 20 minut w wodnym roztworze
kwasu giberelinowego o stężeniu 150 mg dm -3 lub
opryskiwano tym samym stężeniem kłącza jeden, dwa
lub trzy razy, każdorazowo po dokładnym ich obeschnięciu.
Przy każdym opryskiwaniu zużywano 100
ml roztworu. Zastosowano Gibrescol 10 MG. Kwas giberelinowy
zastosowany w formie roztworu do moczenia
kłączy lub ich opryskiwania zadziałał w podobny
sposób. Liczba zabiegów opryskiwania kłączy nie miała
wpływu na efektywność działania kwasu giberelinowego.
U odmiany Black Magic opryskiwanie kłączy
miało podobny wpływ na wcześniejsze kwitnienie,
natomiast u odmiany Cameo podobny efekt uzyskano
mocząc kłącza w kwasie giberelinowym. Kwas giberelinowy
nie wywarł wpływu na jakość kwiatów i liczbę
liści. Kwas giberelinowy wywarł korzystny wpływ
na indeks zazielenienia liści badanych odmian.